Super Best Audio Friends

The evolution of the original irreverent and irrelevant and non-authoritative site for headphone measurements, i.e. frequency response graphs, CSD waterfall plots, subjective gear reviews. Too objective for subjectivists; too subjective for objectivists

I purchased this little T9 amp in July on the advice of my good friend doctorjohn. You can read his original review here:


This unit is really exceptional. It can be purchased from Amazon or your favorite CCCP sponsored online marketplace for around $129 USD. It is worth every penny. I purchased it to use as a stopgap until my single-ended 2A3 project is completed later this year, but I have become so enamoured with it I wonder why one really needs anything more.
I have this on loan. It's overdue. Just a tease for now. Will write some stuff tomorrow. Yes, it's glorious.


In another thread, I can't remember where exactly (readers feel free to point out where I buried it), I posted a list of "Summit-Fi" tube amps I've heard and assigned them rankings per game character builds a la Diablo 3 or Xenoblade (S-tier, A, B, C, etc.). I am still debating whether I actually want to start a formal thread of tube amp rankings because I eschew these kinds of rankings for the following reasons: 1) they greatly oversimplify; 2) audio isn't a game where one or two kinds of character builds will objectively dominate leaderboards; 3) they do not account for personal preferences; 4) they do not account system synergies; 5) they allows readers to take the easy way out, not doing any exploration or research on their own, to just buy what somebody says sounds good, which rarely leads to the exceptional dish.

The Stellaris remains at the top of the leaderboard!
Know about them thanks to @Vtory's profile post.


I love how it looks, resembles a modernized all black Qualia 010 with an orthodynamic driver. What is very interesting is that Final Audio reportedly hired Yamaha (and Sony) engineers to develop the D8000, so this was probably made by the same people that developed the D8000. According to the above article, they want to price it around 400-500k yen (3-3.5k usd in Japanese domestic price, 4k in NA maybe). Weight is only 320gr and should come with two different earpads. It's still in prototype stage according to that japanese article. Ngl this has lots of potential to sound amazing, very excited to see this and hope to hear them one day.
I will update the OP once Zach discloses more information. But I collected all the information I could see in various forums as of today (2022-09-12).


When members of SBAF mentioned the RU6, it did pique my interest. Wow, a portable R2R DAC dongle. Knowing the complexities of R2R design, particularly those that use discrete resistors, and the need to develop suitable oversampling filters (this isn't the 90s anymore where chips were available to do this, and even back then, they took up significant space), I had my doubts.


Like the OG Autuer before, the Auteur Classic is the most "neutral" sounding of the ZMF lineup. The Atrium is bassy, the Verite Open is laid-back, the Verite Closed maybe a bit midcentric, but these three are rich and full sounding. The OG Auteur had been said to be somewhat HD800 sounding (well not that bright, but you get the idea). The Auteur Classic is somewhat like the HD600 of the ZMF lineup. Because my JAR600 are out on loan, I've been using the Atrium and RS-1X (Gerod pads) recently, so it took me while to acclimate to the change. I found the timbre in the highs slightly artificial while using DS DACs, but a switch to a multibit DAC fixed this.


With respect to technicalities and scalability with better upstream components, the Autuer Classic is behind the Atrium and Verite. It's not far off though. This seems appropriate given its about $1k less. Depending upon the recordings one listens to, this may not matter. (I feel a good discussion on source first, amp first, or transducer first is warranted because a lot of this will depend upon the recordings one listens too - and of course one's experience and budget). Now getting back to the HD600 reference? Well the Autuer does share the HD600's small bumps in the presence region and midbass. The lower-mids aren't emphasized so this contributes the clarity aspect. Finally, transient response is somewhere between Atrium and Verite.
The reason I got these was to have Grado RS1 series that weren't too thin sounding. Per my Grado RS-1X review, I found the RS-1X to be thinner in the lows - it did not have the localized mid/upper bass bump of the prior RS1e. See below graph where the 1E (in gray) has a bass bump centered around 160Hz.

Gerod S-Small pads (left) vs standard Grado bowl (right)

While I loved the more resolving driver of the RS1X, and the fancy wood resonance from the triple wood sandwich, I preferred the nice punchy bass bump of the RS1e. So what to do? I think @Philimon turned me on to alternate pads. I know Amazon had a set that were similar to the Grados, but more squishy so they set closer to the ears. These Gerod bowls take a slightly different approach. Taping the standard bowls helped a bit, but this approach seemed ungainly or unwieldy. It felt too cheap, too DIY.

My ultimate goal was just to get back that RS1e bass bump without changing too much else. That is to retain the charm of the RS-1 upper mids (or the terror of it depending upon your point of view). The latest F-cushions worked wonders on the SR-225X and HF2 to make them rather neutral sounding, but simply do not work on the RS1e/x series. The F-cushions on the RS1e/x series results in too dark of a sound with significantly depressed mid-treble. So I took a small gamble on the Gerod pads on Amazon.
It's a different flavor of neutralish compared to the C. Instead of a slight midrange emphasis, the Mini S has low bass emphasis. Subjectively, the bass emphasis is there but not as high as the measurement above would suggest. The bass doesn't intrude into the high bass or lower mids. There's no excess thickness often heard on bassier headphones. There's a very tiny BBC dip going on in the upper mids which I find desirable, especially with natural mic'd recordings in reverberant venues. Note that this BBC dip is the opposite of the Harmon target when it comes to the upper mids.

ETA Mini S
Frequency Response

The Mini S is a semi-open design that often comes with associated usually "better" sonic qualities: snappier transient response, more spacious headstage, improved responsiveness to small signals, etc. The Mini S does scales a bit better the the Mini C with more expensive gear, but like the C, it doesn't need an "amp" or "DAC". It sounds good great from the Android dongle and great from the iFi GO Blu. (Audioslave and STP are sure sounding pretty good and energetic instead of softpoo).
I can't think of any closed headphone (other than a tweaked Sony R10) that did not sound wonky. Usually the higher-end we go, with corresponding superior "technicalities", the wonkier in frequency response it sounds. There are some exceptions at the very high-end, for example with Dan Clark's Stealth, which are tuned toward the Harmon target (for better or worse - I know Dr. Olive's target is not popular here on SBAF), but what about something affordable that sounds tonally correct for a closed headphone?

ETA Mini Closed on left, Mini Semi-Open on right.

Walking around the major film studios in Hollywood, the closed headphone of choice seems to be the ATH-M50x reviewed here. But oh gawd, too much bass. The only closed alternative I can think of is the HD439 which wasn't bad with respect to frequency response, but the sound from it was downright low-fi.

Well, the ETA Mini C is it. More than any other headphone I can think of at this time, the Mini C is the most deserving to have the moniker of "studio headphone". In fact, both my daughter and I have been using the Mini C when we are playing the drums. (And BTW, the Sony MDR7506 don't count either, they sound all sorts of messed up tonally)
This has been an exhaustive review to write, so I’m going to post it a bit brief so we can get the loaner tour going. But I hope it’s enough to give you the idea. There will be a loaner with all 10 of these iems, along with a roll of micropore tape to mod the ones that need it (S12, GL12, PMV PP). Ortho iems in this roundup
  • Audeze Euclid
  • Tin Hifi P2
  • TRN Kirin
  • TFZ Balance 7
  • Gold Planar G12
  • Gold Planar GL20
  • PMV PP
  • Letshouer S12
  • Timeless 7hz
There are a few more out there I did not buy because they cost $1,000 and I have no idea how they sound, or they are ortho/DD or ortho/BA hybrids which is just stupid. Ortho drivers have plenty of extension on both ends and have no problem reproducing the entire FR range with perfection. Theres’ no need for moar drivers. It kind of just defeats one of the great benefits of a single ortho driver which is coherency.

1) Yggdrasil A2 -> Liquid Gold X -> iems
2) Yggdrasil A2 -> Vali 2+ -> iems
3) iphone -> iFI Hip Dac/ Nano BL -> iems
4) iphone -> RU6 -> ems
5) ipod touch 7 -> iems

Tips Used
All iems listened to with Azla Crystal tips except the 7hz which won’t seal with those tips for whatever reason and winds up bass light and trebley. So I used generic Penon tips for those.

Stock Ranking (unmodded)...
The ER-4S was finicky. Most complaints revolved around it sounding too thin, having too much emphasis around the pinna gain region 2-3kHz, and having a small spike in the treble. The secret to using the ER-4S was super deep insertion, usually with the treble flange penetrator tips. Naturally, most people did not like the feeling of having their ear holes penetrated so deeply.

Now what seems like 15 or more years later, the folks at Drop have collaborated with Etymotic to make a new version called the ERX for people who did not want their ear holes assaulted. There's now a normal IEM body instead of a phallic tube. In addition, a set of tips is included that provides a good seal with a good tonal signature (that is not lean or spiky in the highs). At least for me it did. FWIW, I did try the triple flange tip and could not get it to work properly because the body of the IEM prevents deep insertion. Anyway, why did it take so long?

Drop + Etymotic ERX IEM

I would have to say that this is the most agreeable Ety yet to my ears. There's a good amount of bass that extends low. It's not overdone. Of course tastes and gear references vary, thus I can see many IEM users wanting moar bass, moar upper-mids, more treble, a la the Harmon Curve, which this community on average happens to somewhat disagree with (or vehemently disagree when comes to its IE target).